I need to remind you, xingus might be peaceful as juv...but as soon as they hit subadult they can become seriously super anal. Also, don't get just two...get as many as you can. Better chances of pairin up, plus the aggression will be much more subdued. When pikes are below 4" they are relatively delicate, so you will have to keep ur eye on them. Personally, I wouldn't risk pikes of that size in the 125 with those other fish. For one, they are large, have been in there for a while, and could easily harass if not eat the smaller pikes. Also, CA cichlids are more of a hardwater, higher pH fish, so you should really aim to keep them in pHs in the 7.8 to 8.0+....with hard to moderate hard water. They will live in the softer, more acidic pHs...but they are more suited for the higher pHs. I kept my CA cichlids in 8.4 pH and hard water. They loved it. As for the pikes, they can tolerate hard water and higher pHs...but being SA they do show better colors and seem happier in 7.5pH and below.....